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<H1>IBM Visualization Data Explorer Programmer&#39;s Reference</H1>
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<H1><A NAME="HDRPROGLOS" HREF="../proguide.htm#ToC_437">Chapter 18.
Glossary</A></H1>
<P>This glossary defines important
abbreviations and terms.  It includes information from
<CITE>IBM Dictionary of Computing</CITE> (ZC20-1699).
<P>
<TABLE CELLPADDING="3">
<TR><TD COLSPAN="2">A
<P></STRONG></TD></TR><TR VALIGN="TOP"><TD><P>Array
</TD><TD><P>An ordered list of data items of the same type represented
by an Array Object.  Arrays are either irregular or compact.  See
also <I>compact Array, irregular Array</I>.
</TD></TR><TR VALIGN="TOP"><TD><P>attribute
</TD><TD><P>A characteristic of an Object.  Objects can have attributes that
are indexed by a string name and have
a value that is an Object.  See also <I>component attribute</I>.
</TD></TR><TR><TD COLSPAN="2">C
<P></STRONG></TD></TR><TR VALIGN="TOP"><TD><P>cache
</TD><TD><P>The cache service provides various parts of the system with
a means to store the results of computations for later reuse.  Each
cache entry is uniquely identified by a string function name, an
integer key (used by the executive to store multiple
outputs for a single module), the number of input parameters, and the
set of input parameter values.
</TD></TR><TR VALIGN="TOP"><TD><P>camera
</TD><TD><P>A camera defines the position and orientation of the viewer, the
volume of interest of the object being viewed, and the size of the
image to contain the resulting view.
</TD></TR><TR VALIGN="TOP"><TD><P>canvas
</TD><TD><P>The large open area of the VPE window that is used to build and
edit visual programs.
</TD></TR><TR VALIGN="TOP"><TD><P>clipping plane
</TD><TD><P>A plane that divides a
3-dimensional volume into a region that is rendered and
a region that is not rendered.  This allows the inside of an object to
be seen.
</TD></TR><TR VALIGN="TOP"><TD><P>compact array
</TD><TD><P>Any one of five varieties of compact encoding of array data.  The
varieties are&#58;
<UL COMPACT>
<LI>regular
<LI>path
<LI>product
<LI>mesh
<LI>compact.
</UL>
</TD></TR><TR VALIGN="TOP"><TD><P>component
</TD><TD><P>A basic part or classification of a Field; each component is
indexed by a string and its value is an Object.  See
also <I>component attribute</I>.
</TD></TR><TR VALIGN="TOP"><TD><P>component attribute
</TD><TD><P>A characteristic of a component.  Components
of a Field can have attributes that are indexed by a
string name and have a value that is an Object.
</TD></TR><TR VALIGN="TOP"><TD><P>Composite Field
</TD><TD><P>A group of Fields that together is treated a single
Field.
This type of Field is useful, for example, for certain kinds of
simulation data that are represented by disjoint grids.
A Composite Field is a collection of compatible Fields, all having a
"positions" component of the same dimensionality, "data"
components of the same type, and "connections" with the
same "element type."
It is required that members be disjoint and abutting.
</TD></TR><TR VALIGN="TOP"><TD><P>connections
</TD><TD><P>A component of a Field, specifying how data points in that Field
are joined together.
</TD></TR><TR VALIGN="TOP"><TD><P>constant Array
</TD><TD><P>An Array with a constant value.
</TD></TR><TR VALIGN="TOP"><TD><P>contour
</TD><TD><P>Lines on a surface
that connect points with the same data value.
</TD></TR><TR><TD COLSPAN="2">D
<P></STRONG></TD></TR><TR VALIGN="TOP"><TD><P>dependent
</TD><TD><P>A description of a component attribute.  One
component is said to be dependent on another if the items in
the component arrays are in one-to-one correspondence with
each other.
</TD></TR><TR><TD COLSPAN="2">E
<P></STRONG></TD></TR><TR VALIGN="TOP"><TD><P>executive
</TD><TD><P>The component of the Data Explorer system that manages the execution
of
modules specified using the scripting language.  This term is often
used to refer to the entire server portion of the Data Explorer
client-server model, including the executive, modules, and data
management components.
</TD></TR><TR VALIGN="TOP"><TD><P>export
</TD><TD><P>To write an Object to a
specified Data Explorer-format
external data file.  For example, importing an ASCII file can
be slow.  You
can export the data in a binary format for faster access.  You
can also import data, operate
on it, and then export the transformed data for future use.
</TD></TR><TR><TD COLSPAN="2">F
<P></STRONG></TD></TR><TR VALIGN="TOP"><TD><P>Field
</TD><TD><P>A self-contained collection of information necessary
to represent scientific data.  A
Data Explorer Field typically is made up of a series of components
and other information as required.  It
includes the data itself in the form of a "data"
component, a set of sample points in the form of a
"positions" component, optionally,

a set of interpolation elements
in the form of a "connections" component, and other
information as needed.
</TD></TR><TR VALIGN="TOP"><TD><P>filter
</TD><TD><P>A program that converts data to a Data Explorer format.
</TD></TR><TR VALIGN="TOP"><TD><P>flat shading
</TD><TD><P>A shading model in which each polygon of an object is shaded
using a single intensity value.  Contrast with <I>Gouraud shading</I>.
</TD></TR><TR VALIGN="TOP"><TD><P>fork&#45;join parallelism
</TD><TD><P>A programming concept that allows parallel processing.  The fork
statement splits a single computation into multiple
independent computations.  The
join statement recombines two or more concurrent computations
into one.
</TD></TR><TR><TD COLSPAN="2">G
<P></STRONG></TD></TR><TR VALIGN="TOP"><TD><P>glyph
</TD><TD><P>A figure that is mapped to a particular variable.  The
length, angle, or other attribute of the figure
relates to the value of the particular variable.
</TD></TR><TR VALIGN="TOP"><TD><P>Gouraud shading
</TD><TD><P>Also called intensity interpolation shading.  A
shading model in which the intensity of values of incident
illumination on a polygon are interpolated from intensity values at
the vertices of the polygon.  Contrast with <I>flat shading</I>.
</TD></TR><TR VALIGN="TOP"><TD><P>Group
</TD><TD><P>A collection of Objects.
</TD></TR><TR VALIGN="TOP"><TD><P>grow
</TD><TD><P>Add information from neighboring partitions to a Composite Field.
Generally necessary only in a parallel environment.
</TD></TR><TR><TD COLSPAN="2">H
<P></STRONG></TD></TR><TR VALIGN="TOP"><TD><P>handle
</TD><TD><P>A data structure that is a temporary local identifier for an Object.
</TD></TR><TR VALIGN="TOP"><TD><P>hash table
</TD><TD><P>A table of Objects that is accessed with a search
key (the hash value).
</TD></TR><TR VALIGN="TOP"><TD><P>hidden
</TD><TD><P>A module input parameter that does not appear by
default in the module configuration dialog box.  Hidden
parameters are typically those less
commonly used in visual programs.
</TD></TR><TR><TD COLSPAN="2">I
<P></STRONG></TD></TR><TR VALIGN="TOP"><TD><P>Image window
</TD><TD><P>IBM Data Explorer window that displays the image generated by a
visual
program.
</TD></TR><TR VALIGN="TOP"><TD><P>import
</TD><TD><P>To read in an external data file.
</TD></TR><TR VALIGN="TOP"><TD><P>interactor
</TD><TD><P>A Data Explorer device used to manipulate data in order to
change the visual image produced by a program.
<P>See also <I>interactor stand-in</I>.
</TD></TR><TR VALIGN="TOP"><TD><P>interactor stand-in
</TD><TD><P>An icon used in the visual program editor window to represent
an interactor.  Stand-ins are named after the type of data they
accept.  The five types are:
<UL COMPACT>
<LI>integer
<LI>scalar
<LI>string
<LI>selector
<LI>value.
</UL>
</TD></TR><TR VALIGN="TOP"><TD><P>interpolation element
</TD><TD><P>An interpolation element provides a means to interpolate between
a specified set of sample points.  The
set of interpolation elements for a particular Field constitutes
the "connections" component.
</TD></TR><TR VALIGN="TOP"><TD><P>invalid positions and connections
</TD><TD><P>Marked positions and connections that are ignored by modules.
</TD></TR><TR VALIGN="TOP"><TD><P>irregular Array
</TD><TD><P>An Array Object in which the data is stored explicitly, as
opposed to a compact Array.
</TD></TR><TR VALIGN="TOP"><TD><P>isosurface
</TD><TD><P>A surface in
3-dimensional space
that connects points with the same data value.
</TD></TR><TR VALIGN="TOP"><TD><P>item
</TD><TD><P>A single piece of data in an Array Object.
</TD></TR><TR><TD COLSPAN="2">J
<P></STRONG></TD></TR><TR VALIGN="TOP"><TD><P>join
</TD><TD><P>An operation that merges two or more computation paths.
</TD></TR><TR><TD COLSPAN="2">L
<P></STRONG></TD></TR><TR VALIGN="TOP"><TD><P>light
</TD><TD><P>An Object that illuminates a scene.
</TD></TR><TR><TD COLSPAN="2">M
<P></STRONG></TD></TR><TR VALIGN="TOP"><TD><P>macro
</TD><TD><P>In IBM Data Explorer, a
sequence of modules that are be collected together.  A
macro cannot have recursion at any level.
</TD></TR><TR VALIGN="TOP"><TD><P>makefile
</TD><TD><P>A file used by the UNIX&#42;&#42;
utility "make" that contains a
list of source files and commands required for maintaining current
versions of Data Explorer programs.  The
modification times of the files determine what files have changed
since the last time "make" was
run, and therefore, what commands must be executed.
</TD></TR><TR VALIGN="TOP"><TD><P>mdf
</TD><TD><P>See module description file.
</TD></TR><TR VALIGN="TOP"><TD><P>member
</TD><TD><P>An individual unit in a group.  A collection of members makes a
group.
</TD></TR><TR VALIGN="TOP"><TD><P>mesh Array
</TD><TD><P>A compact Array that encodes multidimensional regularity
of connections.  It is a product of connection Arrays.  The
product is a set of interpolation elements in which the product
has one element for each pair of elements in the two multiplicands,
and the number of sample points in each element is the product
of the number of sample points in each of the multiplicands&#39;
elements.
</TD></TR><TR VALIGN="TOP"><TD><P>module
</TD><TD><P>A primitive function that is provided as part of IBM Data Explorer,
such as the Isosurface module.  The
same term is used for the function&#39;s icon, which is its
visible representation in the VPE window.
</TD></TR><TR VALIGN="TOP"><TD><P>Module Builder
</TD><TD><P>A graphical user interface to assist in the creation of
user-defined modules.
</TD></TR><TR VALIGN="TOP"><TD><P>module description file (mdf)
</TD><TD><P>A module description file is used by a programmer who is adding a
module
to Data Explorer to describe
information about the module that
is needed by the system.
<P>A module description file contains the name of the
module, a short description of it, a category for the user interface
to put the module in, and the names and descriptions of the input and
output parameters.  The module description file is used by the
executive and the user interface
to name parameters.  The module description file is also
used by the graphical user interface
to form
a tool icon in the proper category
with the right number of input and output tabs.
</TD></TR><TR VALIGN="TOP"><TD><P>MultiGrid
</TD><TD><P>A MultiGrid Group is another kind of Group that is treated as a
single entity.  Like
a Composite Field, all of the members of a MultiGrid
Group must have the
same type of data and the same type of connections.  It
is <I>not</I> required that members be disjoint and abutting
however.
Overlapping grids can be used along with the "invalid positions"
and "invalid connections" components to define which grid is
valid in a particular region.
</TD></TR><TR><TD COLSPAN="2">N
<P></STRONG></TD></TR><TR VALIGN="TOP"><TD><P>netCDF
</TD><TD><P>See Network Common Data Form.
</TD></TR><TR VALIGN="TOP"><TD><P>Network Common Data Form (netCDF)
</TD><TD><P>A data abstraction
that stores and retrieves scientific data structures
in self&#45;describing, multiple dimensional blocks.  netCDF is
accessible with C or FORTRAN.  netCDF is not a database management
system.
</TD></TR><TR><TD COLSPAN="2">O
<P></STRONG></TD></TR><TR VALIGN="TOP"><TD><P>Object
</TD><TD><P>A region of global memory that contains an identification
of its type plus additional type-dependent information.
</TD></TR><TR><TD COLSPAN="2">P
<P></STRONG></TD></TR><TR VALIGN="TOP"><TD><P>parallelism
</TD><TD><P>The concurrent execution of modules.
</TD></TR><TR VALIGN="TOP"><TD><P>partition
</TD><TD><P>A member of a Composite Field.
</TD></TR><TR VALIGN="TOP"><TD><P>partitioned Field
</TD><TD><P>A Composite Field.
</TD></TR><TR VALIGN="TOP"><TD><P>path array
</TD><TD><P>A compact Array that encodes linear regularity of connections.  It
is a set of <I>n</I> &#45; 1 line segments, where the
<I>i</I>th line segment joins points <I>i</I>
and <I>i</I> &#43; 1.
</TD></TR><TR VALIGN="TOP"><TD><P>pick
</TD><TD><P>One Object that was picked using the mouse.
</TD></TR><TR VALIGN="TOP"><TD><P>pick path
</TD><TD><P>A list of integers that describe how to traverse
an Object&#39;s hierarchy to reach a particular picked
object.
</TD></TR><TR VALIGN="TOP"><TD><P>pick structure
</TD><TD><P>A Field that identifies objects
picked using the mouse.  It contains the components
"positions," "pick paths," "picks,"
and "pokes."
</TD></TR><TR VALIGN="TOP"><TD><P>poke
</TD><TD><P>One screen location that was poked, or selected,
by the user.  One poke may result in none, one, or
more than one pick.
</TD></TR><TR VALIGN="TOP"><TD><P>positions
</TD><TD><P>A component of a Field, consisting of a set of points.
</TD></TR><TR VALIGN="TOP"><TD><P>private Object
</TD><TD><P>Objects containing arbitrarily stored data.  These
Objects can be stored in the cache for later use.
</TD></TR><TR VALIGN="TOP"><TD><P>product Array
</TD><TD><P>A compact Array that encodes multidimensional positional
regularity.  It
is the set of points obtained by summing one point from each
of the terms in all possible combinations.
</TD></TR><TR VALIGN="TOP"><TD><P>pseudo key
</TD><TD><P>Accesses Objects in a hash table.
</TD></TR><TR><TD COLSPAN="2">R
<P></STRONG></TD></TR><TR VALIGN="TOP"><TD><P>realization
</TD><TD><P>The representation of data in terms of boundaries, surfaces,
transparency, color, and other graphical, image,
and geometric characteristics.
</TD></TR><TR VALIGN="TOP"><TD><P>regular Array
</TD><TD><P>A compact Array that is a set of <I>n</I> points lying on a
line with constant spacing between them, representing
1-dimensional regular positions.
</TD></TR><TR VALIGN="TOP"><TD><P>rendering
</TD><TD><P>The generation of an image from some representation
of an object.
Rendering can be done from a surface representation, or from
volumetric information.
</TD></TR><TR VALIGN="TOP"><TD><P>ribbon
</TD><TD><P>Ribbons are derived from lines (e.g., streamlines and
streaklines).
Ribbons may twist to indicate vorticity.
</TD></TR><TR><TD COLSPAN="2">S
<P></STRONG></TD></TR><TR VALIGN="TOP"><TD><P>scripting language
</TD><TD><P>The IBM Data Explorer command-line language.  The
scripting language is available for users who choose to write
visual programs in a programming language.  Data Explorer
uses the scripting language to manage the execution of modules
and to invoke visualization functions.
</TD></TR><TR VALIGN="TOP"><TD><P>Series
</TD><TD><P>A Series is intended to represent a
single Field sampled across some parameter, such as time or temperature
(e.g., a simulation of a CMOS device across a temperature range.
Members of a Series have a position.
A copy of the position is found in the "Series position"
attribute.
<P>
Every member of the Series must have the same dimensionality, say
<I>n</I>, the same data type, and the same connections
element type.
Members are stored in and retrieved from a Series Group
by index rather than by name.
Members cannot be retrieved by Series value.
</TD></TR><TR VALIGN="TOP"><TD><P>shading
</TD><TD><P>Applying lights to a surface during the rendering process.
</TD></TR><TR VALIGN="TOP"><TD><P>shrink
</TD><TD><P>Generally
necessary only in a parallel environment;
deletes the information, previously added by Grow, from
neighboring partitions of a Composite
Field.  Composite Field members are returned to their original size.
</TD></TR><TR VALIGN="TOP"><TD><P>stand-in
</TD><TD><P>See <I>interactor stand-in</I>.
</TD></TR><TR VALIGN="TOP"><TD><P>streaklines
</TD><TD><P>Lines, sometimes called rakes, that show the path of
particles over time.
</TD></TR><TR VALIGN="TOP"><TD><P>string Object
</TD><TD><P>A character string stored in an Object.
</TD></TR><TR><TD COLSPAN="2">T
<P></STRONG></TD></TR><TR VALIGN="TOP"><TD><P>tiling
</TD><TD><P>Combining shaded surface and volume interpolation elements to
produce an image.
</TD></TR><TR VALIGN="TOP"><TD><P>tool
</TD><TD><P>A general term used to describe any of the icons used by
IBM Data Explorer to build a visual program, specifically modules, macros,
or interactor stand-ins.
</TD></TR><TR VALIGN="TOP"><TD><P>tube
</TD><TD><P>Tubes are derived from lines (e.g., streamlines and
streaklines).
Tubes may twist to indicate vorticity.
</TD></TR><TR><TD COLSPAN="2">V
<P></STRONG></TD></TR><TR VALIGN="TOP"><TD><P>value
</TD><TD><P>(1) A specific occurrence of an attribute (e.g.
for the attribute "color").
<BR>(2) A quantity assigned to a constant, a variable, a parameter,
or a symbol.
</TD></TR><TR VALIGN="TOP"><TD><P>visual program
</TD><TD><P>A user-specified interconnection of Data Explorer modules that
performs
a sequence of operations on data.
</TD></TR><TR VALIGN="TOP"><TD><P>Visual Program Editor
</TD><TD><P>Data Explorer graphical user interface for creating and editing
visual
programs and macros.  See also <I>canvas</I>.
</TD></TR><TR VALIGN="TOP"><TD><P>VPE
</TD><TD><P>See Visual Program Editor.
</TD></TR><TR VALIGN="TOP"><TD><P>volume
</TD><TD><P>An object that fills a 3&#45;dimensional space.
A solid ball is a volume.
A surface, however, is infinitely thin and does not fill space
even though it exists in three dimensions.
</TD></TR><TR VALIGN="TOP"><TD><P>volume rendering
</TD><TD><P>A technique for creating an image that
shows not just the surface of a 3&#45;dimensional object,
but its contents as well.  The
interior details being visualized may be physical, such as bone
and muscle in a human body or the structure of a machine part, or they
may be other characteristics such as fluid flow, heat, or stress.
</TD></TR></TABLE>
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